Head and neck cancers frequently spread to lymph nodes in the neck. The treatment of the neck nodes is determined in conjunction with the treatment of the primary cancer in the mouth or throat. In general, relatively early stage neck metastasis (small node or nodes that can be removed completely with an operation) are removed in conjunction with the tumor if the first step in treatment is to be an operation. On the other hand, if the primary cancer is best managed with radiation therapy, the neck nodes are treated with irradiation as well, and if they resolve completely at the end of treatment, surgery is not necessary. On the other hand, if neck nodes remain at the end of radiation therapy, it is safest to proceed with an operation to remove them. This operation is referred to as a neck dissection. Large lymph nodes, particularly those that do not go away completely after radiation therapy, are best treated with a combination of radiation and a neck dissection. A computed tomography scan is used following radiation therapy to determine the probability of remaining cancer and the need for surgery.